一种饱和粘土本构模型的实验研究

本文紧密结合工程应用,基于三轴破坏实验和静水压缩实验结果,采用多项式函数给出了破坏包络线的具体形式,运用椭圆函数确定了加载函数曲线,从而提供一个简便易用,适用于一种饱和粘土的帽子模型。它与实验观测结果的吻合程度是令人满意的。     

Investigation of calculation method for anti-penetration of reactive power steel fiber concrete (RPC)

为了解决评估超高强活性粉末钢纤维混凝土的抗侵彻能力问题，根据混凝土在弹体侵彻过程中的介质状态及能量的分配关系，揭示了侵彻近区耗散能量结构与破碎区之间的比例尺度关系。由于近区介质的运动特性变形接近一维应变状态，受力类似于流体动力学状态，据此推导并简化了具有宽广的适用范围的侵彻计算公式，认为侵彻的深度主要由弹体的质量、形状、速度及靶体的强度、密度、断裂韧度、变形波速决定。通过多次的实弹试验，验证了公式的可靠性，得到了RPC的抗侵彻能力是普通混凝土的3倍的结论。     

花岗岩体中应力波传播计算的动态本构关系

在花岗岩体的弹性区域,对实测径向质点速度波形运用Lagrangian分析方法,得到了球面应力波传播的加载速率相关的应力应变关系曲线。由速率相关本构关系所作的计算结果表明,它能较正确地描述岩石中球面应力波传播过程中所体现的主要特征,即应力波峰值衰减指数大于1和波形剖面的展宽。     

Limitations of the Phan-Thien non-linear network viscoelastic model

The failure of the Phan-Thien non-linear network viscoelastic model to predict realistic stress-strain relationships under certain conditions is illustrated in two examples. Care in the application of the model when applied in situations where high shear rates are expected is indicated.     

Phase equilibrium in non-fluids and non-fluid mixtures

A criterion of phase equilibrium for mixtures of materials with arbitrary symmetry (e.g. between solid and fluid or two solid mixture phases) is deduced using a rational thermodynamics approach. This criterion, known also as Maxwell relation, is expressed via the difference of chemical potential tensors (Eshelby tensors) on the singular surface dividing the bulk phases.The thermomechanical balance equations, the entropy inequality and the Maxwell relation for phase equilibrium are given first for the case of pure (one-constituent) materials of arbitrary symmetry and then for the case of mixtures (including chemically reacting ones) of arbitrary symmetry.In the special case of fluids it is shown that the chemical potential tensors reduce to the classical scalar chemical potentials and the Maxwell relations to the classical thermodynamic criterion for the phase equilibrium.     

Dynamics of strings made of phase-transforming materials

This paper presents a theory to describe the dynamical behavior of a string made of a phase-transforming material like a shape-memory alloy. The study of phase boundaries, the driving force acting on them and the kinetic relation governing their propagation is of central concern. The paper proposes a qualitative experimental test of the notion of a kinetic relation, as well as a simple experimental method for measuring it quantitatively. It presents a numerical method for studying general initial and boundary value problems in strings, and concludes by exploring the use of phase transforming strings to generate motion at very small scales.     

Special properties of Eshelby tensor for a regular polygonal inclusion

When studying the regular polygonal inclusion in 1997, Nozaki and Taya discovered numerically some remarkable properties of Eshelby tensor: Eshelby tensor at the center and the averaged Eshelby tensor over the inclusion domain are equal to that of a circular inclusion and independent of the orientation of the inclusion. Then Kawashita and Nozaki justified the properties mathematically. In the present paper, some other properties of a regular polygonal inclusion are discovered. We find that for an N-fold regular polygonal inclusion except for a square, the arithmetic mean of Eshelby tensors at N rotational symmetrical points in the inclusion is also equal to the Eshelby tensor for a circular inclusion and independent of the orientation of the inclusion. Furthermore, in two corollaries, we point out that Eshelby tensor at the center, the averaged Eshelby tensor over the inclusion domain, and the line integral average of Eshelby tensors along any concentric circle of the inclusion are all identical with the arithmetic mean.The project supported by the National Natural Science Foundation of China (10172003 and 10372003) The English text was polished by Keren Wang.     

考虑裂纹闭合效应的岩石损伤本构关系

岩石中的预存裂纹只有在一定的法向压应力即裂纹闭合应力的作用下才可能闭合，其闭合过程与其方位和外加应力场有关，并且，即使对于裂纹已经完全闭合的岩石，如果裂纹闭合应力不同，则岩石的应力应交关系也不相同。本文建立了考虑裂纹闭合效应的岩石细观损伤力学模型，分析了裂纹闭合应力对岩石损伤演化过程和应力应变关系的影响。数值结果表明裂纹闭合应力显著地改变岩石的应力应变关系，表现为随裂纹闭合应力的增加，岩石的轴向应变变化较小，侧向应变和体积应变则大为增加。     

UNCONVENTIONAL HAMILTON-TYPE VARIATIONAL PRINCIPLES FOR DYNAMICS OF REISSNER SANDWICH PLATE

According to the basic idea of classical yin-yang complementarity and modern dual-complementarity,in a simple and unified way proposed by Luo(1987),some uncon- ventional Hamilton-type variational principles for dynamics of Reissner sandwich plate can be established systematically.The unconventional Hamilton-type variation principle can fully characterize the initial-boundary-value problem of this dynamics.In this pa- per,an important integral relation is given,which can be considered as the generalized principle of virtual work in mechanics.Based on this relation,it is possible not only to obtain the principle of virtual work in dynamics of Reissner sandwich plate,but also to derive systematically the complementary functionals for five-field,two-field and one-field unconventional Hamilton-type variational principles by the generalized Legender trans- formations.Furthermore,with this approach,the intrinsic relationship among the various principles can be explained clearly.     

单边自由的固支岩板黏弹性行为分析及其应用

利用黏弹性理论对单边自由的固支岩板的黏弹性力学行为进行了分析研究，重新导出了相空间中黏弹性参数的变换关系式，并利用此式建立了单边自由的固支岩板的广义Kelvin黏弹性分析格式，将其应用于某层状岩体洞室顶板的变形特性分析．计算表明，其与实际勘察结果比较接近，可供工程实际应用参考．